Calculate vig, overround and no-vig probabilities
Vig, overround and bookmaker margin describe how far a market's combined implied probabilities sit above 100%. Normalisation removes that excess proportionally; it does not prove the resulting probabilities are correct.
Formula and worked example
Book percentage = Sum of (1 / Decimal odds)
Overround = Book percentage - 100%
No-vig probability = Outcome implied probability / Book percentage
A two-way market at 1.80 and 2.10 implies 55.56% and 47.62%. The book percentage is 103.17%, so the overround is 3.17%. Normalisation produces no-vig probabilities of about 53.85% and 46.15%.
Reading the result
Book percentage measures the full set of entered outcomes. Missing an outcome makes the result incomplete. A negative overround can occur when prices from different sources create an arbitrage rather than a conventional single-book market.
Limits and responsible use
The no-vig split is a proportional estimate. It does not model information, bias or execution risk. Settlement and void rules can also change the realised result. See Gambling Commission LCCP 4.2.6.
Set a spending limit before gambling and do not chase losses. Read GambleAware's advice and our responsible gambling guidance.
Related tools and guides
After comparing prices, you can compare betting partners. Oddly Likely may earn a commission from partner links; check current odds, eligibility and terms. Read the affiliate disclosure.
Frequently asked questions
How do you calculate the vig?
Add up the implied probability of every outcome, where each is 1 / decimal odds. The amount by which the total exceeds 100% is the overround, and that is the bookmaker's margin on the market.
What is a normal vig?
Roughly 4% to 5% on a two-way moneyline, and nearer 2% at sharper books. Three-way football markets usually carry more because there are three prices to pad.
What is the difference between vig, overround and hold?
They describe the same thing from different angles. Overround is how far the market's implied probabilities exceed 100%. Vig, or juice, is the charge that creates it. Hold is the share of turnover the book expects to keep.
How do I remove the vig from a price?
Divide each outcome's implied probability by the market total, then convert back to odds. The no-vig calculator does that and returns the fair price for each outcome.
Sources
- Gambling Commission, LCCP condition 4.2.6. Current code accessed 30 July 2026.
- GambleAware, Advice to consider if you're gambling. Accessed 30 July 2026.